When you add a domain, a step-by-step wizard helps you add users and convert your Office 365 email addresses and other services to your business name. When you complete the wizard, your business email starts coming to Office 365 instead of going to your current email provider. To learn more, see Add your users and domains to Office 365. If you use Office 365 operated by 21Vianet, see Verify your domain.
You can add up to 900 domains to your Office 365 subscription. However, you can't add a domain to Office 365 that you're already using in another Microsoft cloud service. That means that you can't add the same domain to multiple Office 365 subscriptions. For more information, see Domains FAQ.
Second and third-level domains
With Office 365 Enterprise and Office 365 Business, you can add any level domain, including third-level domains such as marketing.contoso.com. See Add custom subdomains or multiple domains to Office 365. If you are using Office 365 operated by 21Vianet, see Add custom subdomains or multiple domains to Office 365 operated by 21Vianet.
Domain verification and managing DNS records
With Office 365, you can manage all your DNS records at your DNS hosting provider, or opt to have Office 365 set up and manage your domain's DNS records for you. If you continue to manage the records, you change specific records to point to Office 365 services as needed. For a list of domain registrars for which we provide step-by-step directions for adding the records, including the specific values to use for each record, see Create DNS records for Office 365 or, if you are using Office 365 operated by 21Vianet, see Create DNS records at any provider for Office 365 operated by 21Vianet.
If Office 365 manages your domain's DNS records for you, you first must switch your domain's nameserver records to point to Office 365 and then Office 365 sets up your Office 365 services and then your domain's DNS records are managed at Office 365.
If your domain is registered at GoDaddy, Office 365 can create the required records for you at GoDaddy.
No matter where your DNS records are hosted, you can set up the DNS records to use your domain for the URL for a public website hosted on Office 365 or with a different hosting provider.
Office 365 proactively checks your DNS records to find and help fix DNS issues. If your DNS records don't match what we expect them to be, you'll receive a notification in the Microsoft 365 admin center, along with information that tells you how to fix the possible issues that have been identified.
For more information, see How Office 365 manages DNS records or, for Office 365 operated by 21Vianet, see Create DNS records for Office 365 when you manage your DNS records.
Sharing a domain
You can pilot Office 365 with some email addresses for a domain on Office 365, and some on your previous email provider. This is recommended only for use during a pilot of Office 365, because it requires additional setup steps and has some limitations for Office 365 services. For more information, see:
To view feature availability across Office 365 plans, standalone options, and on-premises solutions, see Office 365 Platform Service Description.